Antweight
From Combat Robot
Antweights in the United States represent the weight class limited to 1 pound. For more information on the 150-gram class, see Fairyweight. For the purposes of this article, "Antweight" will refer to robots with a maximum weight of 1 pound. Antweights are one of the insect classes.
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Design
As one of the largest classes numerically, antweights form a popular class for beginning builders to compete for the first time. Primarily, this is due to availability of parts, but the converse is also true: more businesses have created components that specifically cater to the insect-bot market, fueling growth. The low startup cost possiblity as a result is one of the driving forces behind the growth of the antweight class.
Any weapon type found in other classes can be resized appropriately for the antweight class. Obviously, care must be taken to observe the weight limit, and an accurate balance or scale is often a valuable asset.
Common components
Frame material
A high strength-to-weight ratio is of paramount importance to antweight components, and the frame & chassis is definitely not excluded. Builders reach into more exotic materials such as Carbon fiber panels and composites, which offer a very high strength to weight ratio. High-impact plastics such as Lexan or UHMW-Polyethylene are also used, and are inexpensive. Antweights also use metal armor with Aluminum and Titanium alloys being the most common.
Motors
The realm of antweight motors covers a wide range. Antweights have been built with modified R/C servos, motors and gearboxes from toys, and even the bases of toys themselves. On the other end of the spectrum are precision industrial gearboxes featuring advanced technology and often an exquisite price tag. Around the middle of the range lie general robot-hobbyist type motors such as Tamiya gearboxes and specially-designed, antweight specific motors.
For the most part, antweight weapon motors are derived from R/C hobby model motors for small electric cars, bots, and aircraft. Popular among the kinetic energy weapons are brushless motors which offer an extremely high power-to-weight ratio, an example of which is the AXI line of motors. Also used are small brushed "can" type motors such as the Mabuchi 380 and small rare-earth magnet motors.
Weapons
Almost any weapon that can be found on larger classes can be sized down to an antweight. In fact, many builders have created miniatures of their larger bots to compete in this class.
Kinetic weapons are popular in the antweight class and come in all their forms. One of the more popular designs is the vertical spinner using small handheld circular saw blades or custom-machined blades. Bar spinners are also common in both vertical and horizontal, and even the occasional angled spinner.
Lifter and flipper weapons are also commonly in the antweight class, and can be electric, spring-assisted, or pneumatic. Earlier generations of antweights often used a servo directly mounted to a protruding lifting arm. This design has fell out of favor to high-reduction gearboxes often coupled to the arm through a linkage. Small industrial pneumatic components have also been used in antweights to success, both to lift and flip.
Wedges continue to be an effective force in all classes, and antweights are no exception. This is the simplest design to build, and a "classic" servo-driven antweight can be crafted from a R/C package in under an hour. The servo-wedge, however, has fallen out of favor in modern antweights. More advanced wedge-bots use high-powered drive motors and high-traction wheels in conjunction with heavy armoring.
Speed Controllers
Antweight controllers generally fall into two categories: specialized controllers for drive and hobby controllers for weapon.
The advent of single-board, lightweight, high-power controllers saw an explosion of advanced antweight designs due to the removal of the low power limit of servo controller boards and the lack of very small, reversable hobby controllers. These custom controllers often pack multiple output channels, signal mixing, and an "invert" feature onto a board usually 1.5" square. They often handle up to 5 to 10 amperes of current, enough for almost all antweight drive motors.
The "invert" feature is an important asset for builders of invertable(able to run when flipped over) robots, since motor outputs are automatically reversed to compensate for the bot's rotation.
Weapon controllers once again tap into the realm of R/C hobby components, with brushes and brushless type controllers for small electric airplanes found in antweights. These controllers are often extremely lightweight and have high power throughput.
Batteries
Batteries were once the limiting factor in the design of antweight 'bots due to the low availability of high-current cells light enough to be used in an antweight battery pack.
Modern antweights often use Nickel-metal hydride and lithium polymer batteries to provide high energy density. Lithium packs are particularly popular with small-bot builders due to their space efficiency, power density, and power output.
External Links
Robot Marketplace Antweights Department carries a massive selection of antweight parts. Batteries, controllers, motors, receivers, even frame material.
Barello ANT100 & ANT150 controllers, an example of the bot-specialized controller.
Scorpion HX, another example.
Hobby Lobby's large selection of R/C type motors, brushed and brushless.
